A computer system is a collection of computer components, such as memory, which work together to perform a specific task, and is well known in the art. The computer systems may be located in a single computer, such as a server, or in a plurality of computers, such as a computer network. System administrators (hereinafter, administrators) are people who setup and manage computer systems. One of the tools used by administrators to increase the performance of a computer system is physical partitioning. Administrators physically partition a managed system by dedicating buses and predefined physical modules within the system to assist in creating the smaller partitioned systems, referred to as virtual systems. Each virtual system in a managed system appears to the end user as a completely separate system. In addition, virtual systems improve administrative flexibility and application performance.
Another method used by administrators to increase system performance is logical partitioning. Logical partitioning is a process which creates logical partitions within the managed system. Logical partitioning is distinct from physical partitioning in that there are no physically separated buses, memory, or processors in a logically partitioned system. Instead, the virtual systems are separated only by the system software. Similar to the physically partitioned system, each individual virtual system created by logical partitioning appears to the end user as a completely separate system. One advantage of logical partitioning is that logical partitioning permits much finer granularity in virtual system creation, such that any processor, memory, or adapter may be easily added or removed from a virtual system. Logical partitioning is generally controlled by a hardware management console outside of the managed system. The hardware management console controls the division of the managed system into the virtual systems and, if necessary, the reallocation of resources amongst the various virtual systems.
Recently, administrators have been able to move system hardware resources within the managed system with increased flexibility. When the reallocation occurs without having to reboot the managed system, the logical partitioning is known as dynamic logical partitioning. The prior art methods of dynamic reallocation require the system administrator to recognize the need for reallocation, and then manually reallocate the resources. For example, in a system comprising a first logical partition having eight gigabytes (GB) of memory and a second logical partition also having eight GB of memory, the administrator may observe that during a peak memory-intensive period, the first logical partition is experiencing heavy paging activity while the second logical partition is experiencing light paging activity. Upon observing the disparity in memory paging activity, the administrator may manually move some amount of memory from the second logical partition to the first logical partition to improve system performance during the peak memory-intensive period. Therefore, a need exists for a system and method to automate the control and movement of resources in a dynamic logical partitioning environment.
The need for automation within the reallocation process has been addressed by the prior art. U.S. Pat. No. 4,603,382 (the '382 patent) entitled “Dynamic Buffer Reallocation” discloses a method for dynamically reallocating data storage segments within a storage device. The '382 patent monitors the properties of the data storage device and reallocates the buffer segments when they exceed a predefined threshold. U.S. Pat. No. 5,875,464 (the '464 patent) entitled “Computer System with Private and Shared Partitions in Cache” discloses a partitioned cache memory buffer which monitors the allocation of tasks. The memory buffer of the '464 patent reallocates the tasks when necessary. U.S. Pat. No. 5,978,583 (the '583 patent) discloses a method of reallocating applications during the course of their execution. The method disclosed in the '583 patent monitors the applications and redistributes the applications when necessary based on various criteria. U.S. Pat. No. 6,366,945 (the '945 patent) entitled “Flexible Dynamic Partitioning of Resources in a Cluster Computing Environment” discloses a method for dynamic partitioning of a computer network. The method of the '945 patent monitors the resources within the virtual networks and moves resources among networks when required. However, the '945 patent is limited in that it does not disclose a method for dynamic logical partitioning of a managed network. Consequently, what is needed beyond the '382, '464, '583, and '945 patents is a method and system for dynamic logical partitioning of a managed system. Furthermore, a need exists for a method and system for reallocating resources among the computers within a virtual system.